Sharps disposal system

ABSTRACT

A sharps disposal apparatus is provided for reducing contaminated medical sharps into unrecognizable, ordinary waste. The disposal apparatus comprises a disposal unit including a disposer, disposable waste receptacle, and sterilant recycling system. During the destruction and sterilization operation, the sterilant recycling system introduces sterilant into the disposer to sterilize the contaminated medical sharps while the disposer is grinding the sharps into small fragments. Once the medical waste is reduced to small fragments and is sterilized, the reduced waste is deposited in the disposable waste receptacle. Excess disinfectant flows through the waste receptacle and is recovered by a reservoir to be recycled. After the waste receptacle is full, the waste receptacle is easily removed from disposal unit, without the reduced medical waste coming into contact with human hands, and is disposed as ordinary waste.

RELATED CASES

This application is a continuation of application Ser. No. 08/317,855,filed Oct. 4, 1994, now U.S. Pat. No. 5,470,022, which is a continuationof application Ser. No. 08/143,491, filed Oct. 25, 1993, now U.S. Pat.No. 5,354,000, which is a continuation of application Ser. No.07/876,314, filed May 5, 1992, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a medical waste disposal system and, inparticular, to a disposal system used to destroy and decontaminateinfectious medical sharps. The present invention also relates to amethod of managing infectious or hazardous medical waste.

2. Description of Related Art

The problems attendant to the destruction and decontamination of medicalwaste, such as needles, syringes, vials, plastic blood bags, plastictubes, etc. are formidable. Medical waste presents problems not onlybecause sharps such as needles and syringes are hazardous and difficultto destroy, but also because the waste may be contaminated with viraland bacterial pathogens.

The prevalent practice in the medical community for the disposal ofmedical waste is to throw the waste into specially sealed containerslabeled as hazardous waste. A disposal service periodically collects thecontainers and dumps the containers into huge disposal machines. Thedisposal machines incinerate or pulverize and sterilize the waste fordeposit in a landfill. Unscrupulous disposal services, however, havepreviously illegally dumped unprocessed medical waste into the ocean orlandfills, contaminating the environment.

In an effort to curtail illegal dumping of medical waste, the UnitedStates Congress enacted the Medical Waste Tracking Act, which becameeffective in 1989. The Medical Waste Tracking Act requires medical wastegenerators (i.e., persons or entities producing medical waste) tosegregate waste at their point of origin and package sharps (e.g.,syringes, needles, glass vials, etc.) into rigid, puncture-resistant,leak-resistant containers in order to transport the materials off-site.Generators must also label the untreated waste as medical waste, andmost generators must track (i.e., maintain a written record of) thedisposal process of the waste from the point of origin to the finaldisposal site.

Because of the onerous tracking procedures imposed by the Medical WasteTracking Act and because of the considerable expense associated withdisposal of medical waste, especially sharps, various devices foron-site destruction of used sharps have been developed. These devicestypically grind or otherwise reduce medical sharps into small pieces anddirect the fragments into a receptacle for disposal. For examples, seeU.S. Pat. No. 4,531,437, issued to Szablak, et al.; U.S. Pat. No.4,889,290, issued to Koffsky, et al.; U.S. Pat. No. 4,971,261, issued toSolomons; U.S. Pat. No. 4,984,748, issued to Kimura; and U.S. Pat. No.5,025,994, issued to Maitlen, et al.

In addition, disposal devices have been developed which purport todecontaminate as well as destroy the medical waste. For examples, seeU.S. Pat. No. 4,619,409, issued to Harper, et al.; U.S. Pat. No.4,884,756, issued to Pearson; U.S. Pat. No. 4,889,290, issued toKoffsky, et al.; U.S. Pat. No. 4,971,261, issued to Solomons; and U.S.Pat. No. 5,025,994, issued to Maitlen, et al. Medical waste which hasbeen destroyed and decontaminated on-site can subsequently be disposedas ordinary refuse, thereby reducing the costs associated with off sitedisposal services. The prior disposal systems, however, suffer fromseveral drawbacks.

Many prior disposal systems waste decontaminant, often using moredecontaminant than is required to adequately disinfect the medicalwaste. For instance, the disposal devices disclosed in the Koffsky, etal., and Solomons patents direct both the processed waste and thedecontaminant into disposable receptacles. The excess decontaminantfluid discarded with the medical waste increases the expense of medicalwaste disposal and may pollute ground water when disposed in landfills.

Further, many prior disposal systems do not adequately safeguard thesystem operators, requiring at least some human contact afterintroducing the medical waste. For instance, the disposal systemsdisclosed in the Kimura, Harper et al. and Pearson patents use permanentwaste bins which must be periodically emptied. The Szablak, et al. andKoffsky, et al. patents disclose devices which require the handlers ofthe medical waste to deposit the waste in the disposer unit. Suchdisposal systems are particularly unsuitable for institutionalapplications where relatively unskilled workers are employed to operatethe disposal system. Consequently, prior disposal systems presentpotentially liability issues and may not adequately safeguard theoperators from the infectious medical waste being processed.

Thus, a need exists for a waste disposal apparatus and management systemwhich efficiently, ergonomically and cost effectively reducescontaminated medical sharps to unrecognizable, ordinary waste fordisposal.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, there is provided anapparatus for rendering potentially contaminated sharps into a formsuitable for disposal as ordinary waste. Sharps are initially depositedinto a remote container known in the art as a wall-safe. The sharps arethen fed directly from the wall-safe into a disposer. Liquid sterilantis directed into the disposer and is thoroughly mixed with the sharps todisinfect them as the sharps are ground into a predetermined particlesize.

After the sharps have been ground and disinfected, the particulate wastefalls into a receptacle. The receptacle is a disposable sealablereceptacle which is removed from the apparatus when full andsubsequently sealed and disposed as ordinary waste. The receptacle hasan effluent port near the bottom thereof for drainage of excesssterilant. Excess sterilant which does not adhere to the ground sharpsis recovered by a recirculation system which recycles the sterilant tothe disposer for reuse. Preferably, the receptacle includes a filterdisposed over the effluent port. to prevent escape of processed waste.

In a preferred embodiment, the recirculation system comprises areservoir, typically positioned below the effluent port of the wastereceptacle, to recover excess sterilant. The reservoir is preferably inselective communication with a chemical supply source and with a watersupply source. A microprocessor in communication with a detector is usedto monitor the concentration of a chemical agent in the aqueoussterilant and to automatically introduce fresh chemical agent from thechemical supply source into the sterilant based upon preselectedconcentration criteria.

In another preferred embodiment, the disposer comprises a grindingchamber and a shear ring. The shear ring defines an interior annularsurface and supports an array of spaced teeth which project inwardlytowards the center of the shear ring. Each tooth extends from the shearring interior surface at an angle from and in a plane parallel to acentral vertical axis of the disposer. Each tooth also has a generallyflat bottom surface defining a shearing edge. A plurality of the teethhave top portions extending above the tops of the other teeth and at agreater angle relative to the central axis to define inverted, generallyL-shaped teeth in the array of teeth.

The preferred disposer additionally includes a disk rotatable about thecentral axis. The disk carries a cutter element which forms a shearingsurface and is positioned to engage the shearing surfaces defined by thearray of teeth. The shearing surface of the cutter element cooperateswith the teeth to trap, rip, cut, shear and slice the medical waste intoharmless fragments as the disk rotates.

In accordance with another aspect of the invention, there is provided adisposal system for processing and sterilizing medical waste. Thedisposal system comprises a container having an exit opening and adisposal unit having an opening for receiving materials from thecontainer by way of the exit opening. The disposal system additionally.includes an engagement structure on the disposal unit for engaging thecontainer and placing the exit opening in communication with thedisposal unit opening.

In a preferred embodiment, the container includes an inlet opening todeposit medical waste into the container, a baffle positioned tosubstantially prevent deposited medical waste from spilling through theinlet opening, and a door which normally closes the exit opening. Thecontainer also includes a locking mechanism coupled to the door toprevent unauthorized persons from removing the door from the container.

The preferred engagement structure comprises a pair of rails whichengages the container. The door and the engagement structure also haveat least one interengaging structure which holds the door stationarywhile the container is slid between the rails. The rails are positionedproximate to the opening of the disposal unit such that as the containeris slid with the door remaining substantially stationary, the exitopening of the container is placed into communication with the openingof the disposal unit. The engagement structure automatically opens thedoor of the container to place the exit opening in communication withthe disposal unit opening. The disposal unit additionally comprises adoor normally closing the opening of the disposal unit whichautomatically opens as the engagement structure engages the container.

In accordance with a preferred method of reducing contaminated medicalsharps to unrecognizable, ordinary waste, contaminated medical sharpsare deposited into a disposer and a sterilant is sprayed into thedisposer to generally sterilize the medical sharps. The medical sharpsare ground into small fragments to form a slurry of processed waste andexcess sterilant which is then deposited into a disposable wastereceptacle having at least an influent port and an effluent port.

Excess sterilant is filtered through a filter placed in the receptacleand recovered by a recirculation system which recycles the recoveredsterilant back into the disposer. The waste receptacle is thereaftersealed and removed from the disposer. Preferably, sealing isaccomplished by placing a snap fit or threaded cap over each of theinfluent port and effluent port. The sealed receptacle is thendiscarded.

A further aspect of the present invention involves a method of disposingcontaminated medical waste, such as sharps, accumulated in a medicalfacility, while minimizing human contact with the medical waste. Themethod includes the steps of placing at least one medical wastedepository in the medical facility and thereafter collecting thedepository after medical waste has been placed therein. The depositoryis engaged with a disposal unit and the medical waste is emptied intothe disposal unit. The medical waste is then processed into smallfragments, sterilized, and deposited into a deposable waste receptaclefor disposal.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention will now be described withreference to drawings of a preferred embodiment which is intended toillustrate and not to limit the invention, and in which:

FIG. 1 is a perspective view of a waste disposal system in accordancewith the present invention;

FIG. 2 is a schematic elevational view of the internal components of thewaste disposal system of FIG. 1;

FIG. 3 is a top perspective, partial cut-away view of a wall-safe of thewaste disposal system of FIG. 1;

FIG. 4 is a bottom perspective view of the wall-safe of FIG. 3;

FIG. 5 is a top perspective, partial cut-away view of a secondembodiment of a wall-safe in accordance with the present invention;

FIG. 6 is a bottom perspective view of the wall-safe of FIG. 5;

FIG. 7a is a top perspective, partial cut-away view of the wastedisposal system of FIG. 1, illustrating the interaction between thewall-safe and a disposer unit;

FIG. 7b is a top perspective view of another embodiment of a wastedisposal unit in accordance with the present invention, illustrating anautomated retractable hopper lid;

FIG. 8 is a top perspective, partial cut-away view of a disposer of thewaste disposal unit of FIG. 2;

FIG. 9 is an exploded perspective view of the disposer of FIG. 8;

FIG. 10 is a perspective view of a shear ring of the disposer of FIG. 8;

FIG. 11 is a fragmentary sectional view taken along line 11--11 of FIG.8;

FIG. 12 is side elevational view of a disposable waste receptacle of thewaste disposal system of FIG. 2;

FIG. 13 is a top plan view of the waste receptacle of FIG. 12; and

FIG. 14 is a bottom plan view of the waste receptacle of FIG. 12.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates a medical waste disposal unit 10 in accordance with apreferred embodiment of the present invention. The disposal unit 10processes contaminated medical waste, including sharps, intounrecognizable, ordinary waste. As used herein, "sharps" means sharpmedical waste items, such as, for example, hypodermic syringes orneedles, intravenous needles, Petri dishes, vials and the like.

A compact, rugged stainless steel cabinet 12, mounted on locking casterwheels 14, houses the components of the disposal unit 10. The cabinet 12is preferably sized to unobtrusively fit in a standard size room of amedical facility for on-site disposal of medical waste. More preferably,the cabinet 12 in accordance with one embodiment has the followingdimensions: 36.0 inches (91.4 centimeters (cm)) by 25.0 inches (63.5 cm)by 41 inches (104.1 cm). As will be readily appreciated by one of skillin the art, disposal systems incorporating the present invention can bemanufactured in any of a wide variety of sizes and configurations inaddition to those disclosed herein.

The cabinet 12 includes a front door 15 which provides access to thecontents of cabinet 12. The cabinet 12 also preferably has a removableback panel (not shown) for access into the rear of the disposal unit 10.

The cabinet 12 includes a control and display panel 16 which supports aplurality of indicator lights 18, which alert the operator to thedisposal cycle's status, including an indicator to signal time to removea receptacle filled with decontaminated waste. The specific operation ofthe indicator lights 18 will be discussed below.

FIG. 2 schematically illustrates the components of the disposal unit 10.The disposal unit 10 principally comprises a hopper mechanism 20connected to a disposer 22, a sterilant recirculation system 24 defininga circular fluidic path between a disposable waste receptacle 26 and thedisposer 22, and a program logic computer 28 which controls thefunctioning of the disposer unit 10.

Referring to FIGS. 1 and 2, the hopper mechanism 20 interacts with areusable wall-safe or "mailbox" 30 to receive contaminated wastecollected in the wall-safe 30 from a remote area of the medicalfacility. As used herein, "medical facility" designates a hospital, aphysician or veterinarian office, a medical clinic or a like treatmentfacility which may generate waste of the type which is desirably treatedby destruction and sterilization.

The hopper mechanism 20 communicates with the disposer 22 in a mannerdiscussed in detail infra. Medical waste falls into a grinding chamber32 of the disposer 22 when a retractable gate 34 of the hopper mechanism20 opens. The disposer 22 grinds the medical waste into smallunrecognizable fragments of metal, plastic, glass, etc., thus renderingthe medical waste harmless. The disposer preferably grinds the wasteinto fragments having a size less than 1.0 inch (2.54 cm), morepreferably less than 0.25 inch (0.64 cm), and most preferably less than0.125 inch (0.32 cm) .

During the grinding process, the recirculation system 24 sprayssterilant into the grinding chamber 32 of the disposer 22 tosubstantially sterilize the medical waste in the grinding chamber 32.The ground medical waste and sterilant form a slurry which flows from adischarge port 36 of the disposer 22, through a discharge conduit 38 andinto the disposable waste receptacle 26. A gasket 39 seals theinterconnection between discharge port 36 and the discharge conduit 38.

The disposable waste receptacle 26 receives the slurry of processedmedical waste and sterilant through at least one influent port 40. Themedical waste deposits in a containing cavity defined by the wastereceptacle 26. The waste receptacle 26 also includes at least oneeffluent port 42 through which excess sterilant flows from the wastereceptacle 26. That is, sterilant not adhering to the processed wasteflows through the processed waste and out the effluent port 42. Thewaste receptacle 26 further includes a filter 44 disposed across theflow path through the effluent port 42 to substantially prevent theprocessed waste from escaping through the effluent port 42.

The recirculation system 24 recovers the excess sterilant flowingthrough the effluent port 42 and recycles the sterilant to the disposer22 for further sterilization of additional medical waste placed in thedisposer 22.

The program logic computer 28 preferably monitors each function duringthe destruction and decontamination process and indicates to theoperator when the waste receptacle 26 has been filled. Thereafter, thewaste receptacle 26, filled with ground, unrecognizable, medical waste,is disposed as ordinary waste through conventional means.

The individual components of the medical waste disposal apparatus willnow be discussed in detail. For the purpose of describing the invention,the terms "upper," "lower," "top," "bottom," "forward," "front,""rearward" and "rear" are used in reference to the front door 15 and alower edge 45 of the disposer unit cabinet 12, which are illustrated inFIG. 1.

Wall-Safe

Referring to FIG. 3, the reusable wall-safe 30 has a low profile,configured to be removably mounted on a wall bracket (not shown) in aroom of the medical facility where medical waste may be generated. Thewall bracket and the wall-safe 30 have interconnecting structure whichquickly engages to secure and support the wall-safe 30, and quicklydisengages to remove the wall-safe 30. The interconnecting structurepreferably engages by a snap-fit, pin/key-way connection, press-fit,tab/socket connection or like interconnection.

The wall-safe 30 has a generally rectangular box shape having an inletaperture 46 opening into a holding chamber 48. The holding chamber 48defined by the walls 50 of the wall-safe 30 has a volume ranging between0.5 and 50 quarts (47.3 to 9,730 cm³), more preferably ranging between 1and 10 quarts (94.6 to 946.3 cm³), and most preferably equaling about 5quarts (473 cm³). However, the dimensions and volume of the wall-safecan readily be customized to suit specific facility requirements.

The wall-safe 30 is preferably injection or rotationally molded of adurable plastic material. Preferably, the wall-safe is formed ofpolyvinylchloride ("PVC"), TEFLON®, poly-acrylonitryl-butadienyl-styrene("ABS") or other plastics known in the medical device art. Additionally,the wall-safe is preferably formed of a translucent plastic or with atleast one window therein such that medical facility personnel maydetermine the volume of waste in the container without directly viewingthe waste.

The wall-safe 30 additionally includes a generally cylindrical domecover 51 which precludes direct access into the holding chamber 48. Thedome cover 51 comprises a pair of circular end plates 53 closing theends of a tubular segment 55. The tubular section 55 is sectionedlongitudinally such that the tubular section 55 has a circumferenceextending around about two-thirds of the circumference of the circularend plates 53. The dome cover 51 is coextensive with the inlet aperture46, having a diameter equal to about the width of the inlet aperture 46and having a length equal to about the length of the inlet aperture 46.

The wall-safe 30 includes a pair of semi-circular support plates 57 withextend perpendicularly from a top plate 59 of the wall-safe 30,generally adjacent and parallel to the short sides of the inlet aperture46. The support plates 57 preferably have radii complementary to theradius of the dome cover 51.

A pair of rivets 61 connect the dome cover 51 to the support plates 57and permit the dome cover 51 to rotate within the inlet aperture 46about an axis defined between the rivets 61. The rivets 61 arepreferably positioned at about a radial center point 63 of the supportplates 57 such that cylindrical dome cover 51 does not significantlyextend above the support plates 57. The rivets 61 are preferablypositioned collinear with each other.

The dome cover 51 additionally includes an L-shaped tab 65 to manipulatethe dome cover 51. As illustrated in FIG. 3, the tab 65 is preferablypositioned proximate to a top edge 67 of the tubular section 55 suchthat the tab 65 generally extends upwardly with the interior of the domecover 51 exposed and, as illustrated in FIG. 1, abuts the top plate 59of the wall-safe 30 with the interior of the dome cover 51 concealed.The tab 65 thus limits rotation of the dome cover 51 when closing thedome cover 51. A lower edge 69 of the tubular section 55 abuts the lowersurface of the top plate 59 to limit rotation of the dome cover 51 whenopening the dome cover 51.

Referring to FIG. 4, the wall-safe 30 additionally includes a pair ofbrackets 58 disposed on the lower edges of the rectangular box, alongthe edges of a selectively sealable bottom aperture 60. Each bracket 58has a generally U-shape or V-shape in cross-section, one segment of thebracket extending generally perpendicular to the side wall 50 and theother segment angling back toward the center of the wall-safe at about45°, away from the bottom aperture 60. The brackets 58 thus define apair of parallel slots 62 which receive a slidable bottom tray 64, theside edges 66 of the tray 64 sliding between the pair of parallel slots62. In this manner, the brackets 58 support the tray 64 which closes thebottom aperture 60.

The slidably bottom tray 64 comprises a bottom 71, a front wall 73, apair of side walls 75 and a rear wall 77. The front wall 73 and sidewalls 75 have a height of at least about 0.5 inches (1.3 cm) and thebottom 71 has a size generally coextensive with the bottom aperture 60.The rear wall 77 has a height sufficiently large to abut the adjacentside wall 50 of the wall-safe 30 when the tray 64 is inserted betweenthe brackets 58. The front wall 73, sloping forwardly, preferably formsabout a 15° angle with the bottom 71 and the side walls 75, slopingoutwardly, preferably form about a 45° angle with the bottom 71. Therear wall 77 is preferably positioned generally perpendicular to thebottom 77. As will be readily appreciated by one of skill in the art,however, one could size the walls 73, 75, 77 of the tray 64 and positionthe walls 73, 75, 77 with respect to the bottom 71 at any angle so longas the tray 64 contains any fluid which may drain from the waste and solong as the waste is easily swept out of the tray 64 when the wall-safe30 is slid over the tray 64, as discussed below.

In one preferred embodiment, a disposable, absorbent blotter (not shown)having a fluid resistant surface is positioned on top of the tray 64with the fluid resistant surface contacting the bottom 71. The absorbentblotter completely covers the bottom 71 and desirably extends above thetray walls 73, 75. Consequently, when the wall-safe 30 is slid over thetray 64, the side wall 50 supporting the handle 76 sweeps the blotterout of the tray 64 with the waste.

The blotter preferably comprises an absorbent material, such as, forexample, a sponge, and is coated on its bottom surface with a fluidresistant material, such as, for example, polyethylene. The blotterabsorbs any fluids which may drain from the waste to generally keep theinterior surfaces of the tray 64 free from contaminated fluids.

The tray 64 selectively seals the bottom aperture 60. The tray 64defines an area between the upper edges of the front wall 73, side walls75 and rear wall 77 which is coextensive with the area of the bottomaperture 60. Any fluid which drains from the waste deposited into thewall-safe 30 collects on the bottom 71 of tray 64 or in the blotter, ifused. The walls 73, 75, 77 of the tray 64 contain the fluid. Inaddition, the labyrinth defined between the walls of the tray 64 and thebrackets 58 generally prevents fluid from escaping between the tray 64and the bottom aperture 60. It is also contemplated that a sealingmember could be disposed around the interface between the tray 64 andthe bottom aperture 60 to enhance the seal around the bottom aperture60.

The bottom tray 64 preferably includes a locking mechanism 68 to preventunauthorized persons from removing the tray 64 from the wall-safe 30.The locking mechanism 68 preferably comprises a conventional lockcylinder 70 coupled to a throw lever 72 which rotates in and out ofengagement with the adjacent side wall 50 of the wall-safe 30 to lockand unlock the tray 64, respectively. The locking mechanism ispreferably mounted to the rear wall 77 of the tray 64. The wall-safe 30,proximate the locking mechanism 68, includes an aperture (not shown)which receives the lock cylinder 70 and throw lever 72 when the tray 64is inserted between the lower brackets 58.

The tray 64 also includes a pair of cylindrical pegs 74 which extendfrom the bottom surface of the tray 64, away from the wall-safe 30. Thepegs 74 interact with the hopper mechanism 20, as discussed below.

The wall-safe 30 further includes a handle 76 to facilitate carrying thereusable wall-safe 30 between the mounting bracket (not shown)positioned in the medical facility room and the disposer unit 10preferably located in a remote location of the medical facility.

FIGS. 5 and 6 illustrate an alternative embodiment of a wall-safe 30afor use with the present invention. Where appropriate, like numbers withan "a" suffix are used to indicated like parts of the two embodimentsfor ease of understanding. The wall-safe 30a has a generally rectangularbox shape having an inlet aperture 46a opening into a holding chamber48a. The holding chamber 48a defined by the walls 50a of the wall-safe30a has a volume ranging between 0.5 and 50 quarts (47.3 to 9,730 cm³) ,more preferably ranging between 1 and 10 quarts (94.6 to 946.3 cm³) ,and most preferably equaling about 5 quarts (473 cm³). However, thedimensions and volume of the wall-safe 30a can readily be customized tosuit specific facility requirements.

The wall-safe 30a additionally includes a pair of baffles 52, 54positioned to allow medical waste to fall into the holding chamber 48awhen deposited through the inlet aperture 46a. Baffles 52, 54 arepositioned to substantially prevent deposited medical waste fromspilling out the inlet aperture 46a if the wall-safe 30 is inadvertentlytipped. Each baffle 52, 54 extends inwardly from the side walls 50a ofthe wall-safe 30a generally at an angle of about 45°±30°, and morepreferably at about 30° from the plane of the side wall 50a to form adownwardly inclined ramp.

In a preferred embodiment, the generally rectangular box configurationof the wall-safe 30a has a height of about 11.5 inches (29.2 cm), adepth of about 4.0 inches (10.2 cm), and a width of about 7.75 inches(19.7 cm). The inlet aperture 46a in the illustrated embodiment has arectangular configuration of about 2.0 inches (5.1 cm) by about 7.5inches (19.1 cm). The wall-safe 30a includes a first baffle 52 extendingfrom an upper corner 56 of the wall-safe 30a and projecting downwardlytowards the holding chamber 48a at an angle of about 30°. The firstbaffle 52 spans the length of the wall-safe 30a with a length of about7.75 inches (29.2 cm) and projects into the holding chamber 48a with awidth of about 4.0 inches (10.2 cm).

The wall-safe 30a additionally includes a second baffle 54 attached tothe walls 50a of the wall-safe 30a at a position of about 3.0 inches(7.62 cm) from the top of the wall-safe 30a, opposite the first baffle52, and extending at an angle of about 30° from the side wall 50a of thewall-safe 30a. The second baffle 54 spans the length of the wall-safe30a with a length of about 7.75 inches (29.2 cm), and projects into theinterior of the holding chamber 48a with a width of about 4.0 inches(10.2 cm). The first baffle 52 and the second baffle 54 consequentlyseparate the holding chamber 48a from the inlet aperture 46a. Theholding chamber 48a, configured accordingly, holds about 5 quarts (473cm³) of waste material.

Referring to FIG. 6, the wall-safe 30a additionally includes a pair ofbrackets 58a disposed on the lower edges of the rectangular box, alongthe edges of a selectively sealable bottom aperture 60a. The brackets58a define a pair of parallel slots 62a which receive a slidable door84, the side edges 86 of the door 84 sliding between the pair ofparallel slots 62a. In this manner, the brackets 58a support the door 84which closes the bottom aperture 60a.

The door 84 preferably includes a locking mechanism 68a to preventunauthorized persons from removing the door 84 from the wall-safe 30a.The locking mechanism 68a preferably comprises a conventional lockcylinder 70a coupled to a throw lever 72a which rotates in and out ofengagement with the adjacent side wall 50a of the wall-safe 30a to lockand unlock the door 84, respectively. The wall-safe 30a, proximate thelocking mechanism 68a , includes an aperture (not shown) which receivesthe lock cylinder 70a and throw lever 72a when the door 84 is insertedbetween the lower brackets 58a.

The door 84 also includes a pair of cylindrical pegs 74a which extendfrom the bottom surface of the door 84, away from the wall-safe 30a. Thepegs 74a interact with the hopper mechanism 20, as discussed in detailbelow.

The wall-safe 30a further includes a handle 76a to facilitate carryingthe reusable wall-safe 30a between the mounting bracket (not shown)positioned in the medical facility room and the disposer unit 10preferably located in a remote location of the medical facility.

As illustrated in FIG. 5, a disposable tray 78 is preferably positionedin the wall-safe 30a to prevent fluids, which drain from the medicalwaste, from spilling through spaces between door 84 and the wall-safebottom aperture 60a. Preferably, the tray comprises cellophane or otherconveniently disposable material.

The tray 78 is defined by four side walls 80 having a height of at leastabout 1.5 inches (3.8 cm) and a bottom 82 having a size generallycoextensive with the bottom aperture 60a. The disposable tray 78 ispreferably positioned on top of the bottom door 84 with the wall-safe30a initially empty and is disposed with the medical waste when thewall-safe 30a is emptied into the disposer unit 10, as discussed below.

Hopper Mechanism

Referring to FIGS. 1 and 5, the hopper mechanism 20 includes a platform90 mounted on a top surface 92 of the cabinet 12. The platform 90 isprovided with a central aperture 94 having a shape complementary to thatof the wall-safe bottom aperture 60. The platform 90 further includes apair of parallel rails 96 running along the sides of the centralaperture 94 and being configured to receive the lower brackets 58 of thewall-safe 30. The rails 96 extend from a position proximate the frontside of the central aperture and extend along the length of the centralaperture 94. The platform 90 further includes a pair of holes 98positioned in front of the central aperture 94 and spaced apart by anamount equal to the spacing between the pegs 74 of the wall-safe door64.

The platform is preferably formed from an inert, durable material, suchas, for example, a ultra high molecular weight polycarbonate, stainlesssteel or like material.

As best seen in FIG. 1, a lid 99 covers the central aperture 94 and ismanually pivotable about a hinge 101 to expose the central aperture 94.The lid 99 includes a handle 103 to facilitate opening and closing thelid 99.

Alternatively, as illustrated in FIG. 7b, the hopper mechanism 20includes a retractable lid 100 covering the central aperture 94 andbeing driven by a motor via a rack and pinion mechanism (not shown). Themotor is connected to a micro-switch 102 positioned adjacent to one ofthe platform rails 96. The micro-switch 102 is activated by sliding thewall-safe 30 between the rails 96, as discussed in detail below.Alternatively, the lid 100 is driven by a magnetic mechanism, activatedwhen the wall-safe 30 is placed between the platform rails 96.

Referring to FIG. 2, the central aperture 94 of the platform 90 opensinto a disposer chute 104, which connects the platform aperture 94 withan inlet 106 of the disposer 22. The disposer chute 104 preferably has arectangular cross-sectional shape corresponding to the shape of theplatform aperture 94. The hopper mechanism 20 also includes theretractable gate 34 positioned between the platform aperture 94 and thedisposer inlet 106. The retractable gate 34 is connected to a motor 108via a rack and pinion mechanism 110 which slides the gate 34 from aclosed position to an open position to place an upper portion 112 of thechute 104 above the gate 34 in communication with the disposer inlet106. The motor 108 is connected to the program logic computer 28 whichopens and closes the gate 34, according to the operation sequence. Thehopper gate 34 prevents splash-back of the fluid in the disposer 22 whenthe medical waste is emptied from the wall-safe 30, as discussed indetail below.

The chute upper portion 112 preferably holds a volume of medical wastepreferably equal to the volume held by the wall-safe 30, and morepreferably holds a volume of about 5 quarts (473 cm³) of medical waste.

The Disposer

Referring to FIGS. 8 and 9, the disposer 22 comprises the upper grindingchamber 32 defined by an upper housing portion 120, a cutting assembly122 including a shear ring 124 to reduce the medical waste deposited inthe grinding chamber 32, and a lower discharge chamber 126 defined by alower housing portion 128 which receives the reduced materials anddirects the materials through the discharge port 36 connected to thedischarge conduit 38.

The upper and lower housing portions 120, 128 form a hollow metalhousing, sealed by a central gasket 129. The upper housing portion 120is generally cylindrical shaped and supports an annular top flange 130which circumscribes the inlet opening 106. The bottom housing portion128 is generally cup-shaped and includes a central bottom opening 132positioned coaxially with the cylindrical top portion 120 of thehousing. As seen in FIG. 8, the top and bottom housing portions 120, 128are connected together by a plurality of bolts 134 and cooperateinternally to define an annular recess for tightly receiving and holdingthe shear ring 124 positioned concentrically about the central axis ofthe housing.

Referring to FIGS. 8 and 10, the shear ring 124 includes a series ofspaced cutting teeth 136 extending from and carried by an internal wall138 of the shear ring 124. Each cutting tooth 136 extends at an anglefrom the central axis of the disposer 22, preferably by about 15° to75°, more preferably by about 30° to 60°, and most preferably by about45°. Each tooth 136 is also positioned in a plane parallel to thecentral axis, with the axis of the inner arcuate surface 138 of theshear ring 124 being collinear with the central axis. Every sixth tooth140 of the shear ring 124 includes a top portion 142 which extends abovethe tops of the adjacent tooth 136 in a generally horizontal plane toform a plurality of inverted, generally L-shaped teeth 140 in a seriesof teeth 136. Separated from each L-shaped tooth 140 by a single tooth136 is an elongated tooth 144 which extends the axial height of theshear ring 124 and includes an enlarged upwardly inclined top portion146 above the tops of the other teeth 136, 140 in the series. TheL-shaped teeth 140 and the enlarged teeth 144 trap and direct wastematerials between the other teeth 136 of the shear ring 124 andcooperate with the balance of the cutter assembly 122 to enable thedisposer 22 to rapidly and reliably reduce the medical sharps into smallfragments or into unrecognizable waste, as discussed below. Theillustrated form of the shear ring 124 has proven to be the optimalarray of teeth 136 for this purpose.

Referring to FIGS. 8 and 9, the cutter assembly 122 further includes adisk or flywheel 148 of a slightly smaller outer diameter than the innerdiameter of the shear ring 124. The disk 148 is connected to an upperend of a vertical drive shaft 150 of a motor 152 to turn about thecentral axis of the disposer 22 within the shear ring 124. In thisregard, the vertical drive shaft 150 of the motor 152 extends upwardlythrough the bottom opening 132 in the lower housing portion 128 alongthe central axis thereof and through a seal assembly 153.

The seal assembly 153 supports the drive shaft 150 and seals the loweraperture of the discharge chamber 126. The seal assembly 153 preferablycomprises a fluoroelastomer (e.g., VITON®) O-ring 155 sandwiched betweena bronze mating ring 157 and a seal head 159. The seal head 159 ispreferably a Buna-n and Graphite ring. The seal assembly 153 ispositioned inside a seal cavity 161 of the lower housing 128. With thedrive shaft 150 passing through the seal assembly 151, a spring 163 isplaced over the drive shaft 150 and is held between the seal head 159and a cap 165. The spring biases the seal assembly 153 against a lowerflange 167 of the seal chamber 161. The disk 148 attached to the end ofthe drive shaft 150 to secure the cap 165 in place.

The motor 152 preferably has a 1.5 to 10 horsepower (hp) (1120 to 7460watts (W)) capacity, depending upon the volume of waste materialdesirably being processed during a single disposal cycle. The motor 152is connected to and extends downwardly from the bottom of the lowerhousing portion 128 and carries a plurality of feet 154 which areanchored to the bottom of the cabinet 12.

The disk 148 support is a plurality of cutting blocks 156 and associatedcutting blades 158 positioned around the circumference of the disk 148and positioned adjacent to the lower portion of the shear ring 124 inthe assembly. A plurality of bolts 164 fasten the cutting blocks 156 andcutting blades 158 to the disk 148. As illustrated in FIG. 11, thecutting blocks 156 are angled slightly such that only one vertical edgeof the block 156 engages the inner surfaces of the teeth 136 as the disk148 turns.

With this arrangement of the cutter assembly 122, the medical wastedeposited into the disposer 22 through the inlet opening 106 falls onthe top of the disk 148. Operation of the motor 152 rapidly rotates thedisk 148 in a counterclockwise direction in the illustrated form. Atleast one hammer 160 extends upwardly from the top of the disk 148 tostrike and break up large objects as the disk 148 turns. The hammer 160also acts with the centrifugal force developed by the disk 148 to throwthe waste material rapidly outwardly against the inner wall 138 of thering shear 124. Simultaneously, the waste material is carried by thedisk 148 in a circular path against the teeth 136 of the shear ring 124.

As the waste material rotates with the disk 148, it is captured anddownwardly directed between the other teeth 136 of the shear ring 124 bythe L-shaped teeth 140, as well as by the enlarged teeth 144. Thecaptured waste material is then repeatedly sheared by the vertical teethof the cutting blocks 156 as they travel around and are in contact withthe inner faces of the teeth 136. The sheared material passes downwardlybelow the shear ring 124 between the teeth 136 thereof. There, thematerial is sheared a second time by the cutter blades 156 carried bythe disk 148. This double shearing action reduces even the most densewaste material and allows the material to flow with the sterilantbetween the outer edge of the disk 148 and the bottom of the ring 124into the lower discharge chamber 126. From the discharge chamber 126,the slurry of waste material and sterilant flows through the dischargeport 36 and through the discharge conduit 38 into the waste receptacle26.

When the waste material has been completely reduced and disposed by thecutter assembly 122, the disposer 22 may be internally cleaned bycontinuing to run sterilant therethrough, with drains between the outeredges of the disk 148 and the shear ring 124 and through drain ports 162in the disk 148. The drain ports 162 prevent sterilant from accumulatingwithin the disposer 22 after the disposer 22 has been turned off.

In practice, the continual capturing and shearing between the cutterblocks 156, the angle teeth 136 and L-shaped teeth 140 of the cutterring 124, as well as the shearing action between the bottoms of theteeth 136 and the cutter blades 158, has been found to rapidly reducemedical waste into either small fragments or into harmless, twistedpieces. In this respect, the illustrated array of teeth 136, inclined at45° angles, and including space arrangements of L-shaped and enlargedteeth 140, 144 has proven to provide optimum waste reducing results.

Waste Receptacle

Referring to FIGS. 12 through 14, the disposable waste receptacle 26 hasa durable, hollow plastic body formed by a generally cubic upper portion170 and a generally funnel-liked shaped (i.e., generally invertedpyramidical shaped) lower portion 172. The lower portion 172 has a topsection 174 with a generally square cross-sectional shape correspondingto the cross-sectional shape of the upper portion 170. The lower portion172 tapers in cross section from the generally square top section to agenerally circular bottom section, terminating into the effluent port42. As best seen in FIG. 12, the lower portion 172 thus has asignificantly smaller cross-sectional area proximate the effluent port42 than it has proximate the upper portion 170 to maximize drainagethrough the waste receptacle 26.

The waste receptacle 26 defines an internal volume ranging between 1 and100 quarts (94.6 and 9,463.5 cm³), more preferably ranging between 10and 50 quarts (946.3 and 4,730 cm³), and most preferable ranging between35 and 40 quarts (3,310 and 3,780 cm³).

The waste receptacle 26 further includes the influent port 40communicating with the upper portion 170 of the waste receptacle 26. Theinfluent port 40 supports an external thread 176 configured to engage atop end cap 178 which closes the influent port. Alternatively, the topcap 178 could snap onto the influent port 40, the components 40, 178having cooperating structure as known in the art. The waste receptacle26 also comprises a handle 180 attached between the upper portion 170and the influent port 40 to ease handling the waste receptacle 26.

The waste receptacle 26 includes a rib 182 having a generallyrectangular shape and circumscribing the exterior of the wastereceptacle body 26. The rib 182 is defined between a generally flatupper surface 184 and a generally flat lower portion 186. The rib 182preferably includes a flat label surface 188 to facilitate labeling thewaste receptacle 26.

The waste receptacle 26, at its lower end, attaches to the effluent port42 which projects away from the body. The effluent port 42 supports anexternal thread 192 configured to engage a lower end cap 194 to seal thewaste receptacle 26. The lower cap 194 could alternatively snap onto theeffluent port, the components 42, 194 having cooperating structures asknown in the art.

As best seen in FIG. 13, the longitudinal axes of the influent port 40and the effluent port 42 are off-set from each other. That is, the axesof each port 40, 42 are parallel, but not collinear. The slurry ofprocessed medical waste and sterilant thus strikes the side portion 196of the receptacle 26 before flowing into the filter 44 to improve theperformance of the filter 44.

The waste receptacle 26 further includes a filter 44 preferably disposedwithin the effluent port 42. In one embodiment, the filter 44 has ahollow frusto-conical shape having a plurality of apertures disposedover its surfaces. The frusto-conical shape increases the surface areaof the filter, as compared to a filter spanning across the open end ofthe effluent port 42.

As illustrated in FIG. 14, the filter 44 includes a plurality of smallapertures 198 extending through its upper surface 200. The filter 44also includes a plurality of longitudinal slots 202 extending throughthe side wall 204 of the filter 44 and each being positioned generallywithin a plane that includes the longitudinal axis of the frusto-conicalshape. The filter 44 also comprises a small spacing mesh (not shown)positioned over the side wall 204 of the filter 44. The mesh 204preferably has a grid spacing of 3/16 inch (0.47 cm) on center with ahole size of 1/16 inch (0.16 cm).

As illustrated in phantom lines in FIG. 12, the filter 44 projects intothe lower portion 172 of the receptacle 26 from the lower end of theeffluent port 42. The filter 44 substantially prevents the groundmedical waste from escaping through the effluent port 42 as the excesssterilant flows through the port 42.

Referring to FIG. 2, the waste receptacle 26 is positioned proximate tothe disposer 22 and in communication with the disposer 22 via thedischarge conduit 38. The waste receptacle 26 is supported within thedisposer unit 10 by a pair of brackets 206 which embrace the rib 182 ofthe receptacle body 26. The brackets 206 are preferably mounted on apair of vibrators 208 which support the lower planar surface 186 of thewaste receptacle rib 182. The vibrators 208 vibrate the waste receptacle26 during use to enhance sterilant flow through the waste receptacle 26and to level the waste deposited in the waste receptacle 26.

Sterilant Recirculation System

Referring to FIG. 2, the sterilant recirculation system 24 includes aholding tank or reservoir 220 positioned below the waste receptacle 26which receives the sterilant flowing through the effluent port 42. Theholding tank 220 has a volume capacity ranging between 1 gallon and 50gallons (378 and 18900 cm³), preferably ranging between 5 and 10 gallons(1890 and 3780 cm³), and most preferably equal to about 7 gallons (1890cm³). The holding tank 220 includes a quick dump drain 222 positioned atthe bottom of the tank 220 and includes an incline bottom 224 taperingto the drain 222. A conventional gate valve 226 opens and closes thedrain 222. The holding tank 220 further includes a pair of filters (notshown) positioned in series and disposed between the effluent port 42and an outlet port 228 of the holding tank 220 in order to trap anyground waste which passes through the filter 44 of the waste receptacle26.

The recirculation system 24 further includes a pump 230 in communicationwith the holding tank 220 via the holding tank outlet port 228. The pump230 pumps the recovered sterilant through a return line 232 connected tothe disposer grinder chamber 32 where the sterilant is sprayed into thedisposer 22. The pump 230 preferably has a capacity of 960 gallons perhour (3.63 meter³ /hour) and is corrosion resistant. The pump 230 morepreferably is a Little Giant® model #4-MD-HC pump, commerciallyavailable from the Little Giant® Pump Company.

The holding tank 220 also communicates with a chemical tank 234 whichholds a chemical component of the sterilant. The chemical tank 234preferably hold about 7 to 8 gallons (approximately 0.026 m³) and isfilled through a stand pipe (not shown) accessible through a top cap 236(FIG. 1) located on the panel 16 of the cabinet 12.

A pump 238 is positioned between the holding tank 220 and the chemicaltank 234 to supply fresh chemical such as chlorine to the holding tank220 either after dumping the contents of the holding tank 220 or afterthe concentration of chlorine in the aqueous solution drops below apreselected concentration level, as discussed in detail below. The pump238 is preferably a low flow, corrosive resistant pump, such as the typecommercially available from the Little Giant® Company.

The holding tank 220 further selectively communicates with a pressurizedwater source (not shown), such as a standard water inlet line of themedical facility. A solenoid valve (not shown) connected to the waterinlet line controls the flow of water into the tank 220, primarilyduring a refill sequence, as discussed below.

Preferably, the recommended concentration of sterilant automaticallyflushes waste, insuring safe and efficient sterilization during theduration of each disposal cycle. The sterilant preferably comprises achlorine compound, and more preferably a sodium hypochlorite solution toinactivate vegetative bacteria, fungi, viruses and mycobacteriacontaminating the medical waste. Sodium chlorite solutions with variableconcentrations of free, available chlorine have been shown to inactivatea variety of bacterial spores. Such inactivation is dependant upon theinitial concentration of free, available chlorine, the Ph, thetemperature, the length of time of contact with the spores and thepresence of interfering substances such as organic material. Ideally, achemical germicide used for medical waste treatment should qualify as ahigh level disinfectant (i.e., relative sterilization) with the abilityto kill vegetative bacteria, fungi, viruses, and mycobacteria. It shouldalso have the ability to inactivate a minimum of 10,000 bacteria spores,and maintain sanitability over time. The sporicidal capacity of highconcentrations of sodium hypochlorite (e.g., 2,750 and 5,550 parts permillion (ppm) of free, available chlorine) under severe organic materialchallenge and dissolution has demonstrated to be effective when used inmechanical/chemical medical waste treatment systems. Thus, it ispreferred that the sterilant comprise sodium hypochlorite having aconcentration of free, available chlorine ranging between 2,750 and5,550 ppm, although other concentrations and chemical systems can bereadily identified through routine experimentation by one of skill inthe art.

Control System

Referring to FIG. 2, the program logic computer 28 controls theoperation of the disposer unit 10. The program logic computer 28preferably comprises a programmable controller, such as the D100micro-programmable logic controller commercially available fromCutler-Hammer and distributed through Eaton. The computer 28 is astand-alone programmable logic controller containing a centralprocessing unit (CPU), power supply, memory, and input/output circuitrywith terminals. The controller 28 also contains RAM memory and a back-upbattery. The controller 28 is preferably capable of communicating with apersonal computer (not shown), such as, for example, an XT or ATcompatible computer, or the like, with supporting extended industrystandard architecture, in order to facilitate programming.

The program logic computer 28 is connected to a plurality ofelectro-mechanical mechanisms which sense and control various componentsof the disposer unit 10. The program logic computer 28 is connected to amicro-switch or rocker switch 250 positioned proximate the platformaperture 94, activation of which begins the disposal cycle. Themicro-switch 250 is activated when the wall-safe 30 is positionedbetween the platform rails 96 and slid over the open platform aperture94. The program logic computer 28 shuts off all components of thedisposal unit 10 if the wall-safe is disengaged from the rocker switch250 by sliding the wall-safe 30 from an engagement position covering thecentral aperture 94.

With the wall-safe 30 actuating the rocker switch 250, the program logiccomputer 28 communicates with a level sensor 252 to determine whetherthe chemical tank 234 is above an acceptable level (e.g., is generallyabout one-third full). The program logic computer 28 activates a displaylight 18 when the chemical tank 243 is below a specific level toindicate that the chemical tank 234 needs filling.

The program logic computer 28 also determines when the waste receptacle26 is full. The program logic computer 28 keeps track of the number ofdisposal cycles performed between changings of the waste receptacle 26.That is, after a new waste receptacle has been inserted into thedisposer unit 10, the program logic computer 28 counts the number oftimes that the disposer 22 has been activated in order to determine whenthe waste receptacle 26 is full. With a waste receptacle 26 having aholding capacity of about 35 to 40 quarts (3310 to 3780 cm³), and with adisposal unit 10 being designed for processing about 5 quarts (473 cm³)of waste material during a single disposal cycle, the waste receptacle26 becomes full after about eight (8) disposal cycles. When the programlogic computer 28 determines that the disposer unit 10 has gone througheight (8) disposal cycles from the last changing of the waste receptacle26, the program logic computer 28 activates a panel light 18 to indicatethat the waste receptacle 26 needs to be changed.

Moreover, the program logic computer 28 will not activate the disposerunit 10 until the waste receptacle 26 has been changed and a resetbutton 254 inside the disposer unit cabinet 12 has been actuated.Although FIG. 2 illustrates the reset button 254 as a push button, of atype commercially available from Allen-Bradly, it is contemplated thatthe reset button 254 could comprise a rocker switch or other proximitysensing mechanism mounted proximate to the waste receptacle bracket 206to sense when the waste receptacle 26 has been replaced. After changingof the waste receptacle 26 and actuating of the reset button 254, theprogram logic computer 28 begins the next counting cycle by resetting toits counter to zero and counting up again.

The program logic computer 28 also controls the concentration of thechlorine in the sterilant. After removing the filled waste receptacle26, the sterilant in the holding tank 220 is preferably dumped, asdiscussed in detail below. Thereafter, the program logic computer 28automatically fills the holding tank 220 with sterilant, mixing adesired ratio of water from the supply line with the chemical agentcontained in the chemical tank 234. Specifically, the program logiccomputer 28 energizes the solenoid valve connected between the watersupply line and the holding tank 220. The solenoid valve remains openfor a preselected period of time until the holding tank 220 contains thedesired amount of water. The program logic computer 28, eithersimultaneously or in sequence, activates the pump 238 positioned betweenthe chemical tank 234 and the holding tank 220, to pump the chlorineinto the holding tank 220 in the desired ratio. Consequently, thesterilant generally has a concentration level of chlorine above thepreselected concentration criteria discussed above.

Additionally, the program logic computer 28 preferably communicates witha chlorine concentration monitoring device 256, such as, for example, achlorine specific electrode meter, commercially available from Corning®and distributed by Fisher-Scientific. The monitor 256 preferablyincludes a conventional RS-232-C serial port to digitally communicatewith the program logic computer 28. The monitor 256 senses theconcentration of free, available chlorine ions in the aqueous solutioncontained in the holding tank 220. If the level of free, availablechlorine falls below the preselected concentration levels discussedabove, the program logic computer 28 activates the chemical pump 238 topump a specific amount of chorine into the holding tank 220, therebybringing the concentration level of chlorine above the desiredconcentration level.

The program logic computer 28 also communicates with the motor 152 ofthe disposer 22 through conventional electronic circuitry to determineif the disposer 22 is free from obstructions. If the motor 252 is notfunctioning, the program logic computer 28 activates a display light 18on the panel 16 of the disposer unit 22 to indicate that the disposer 22is jammed. The program logic computer 28 will not activate the disposerunit 10 until the disposer 22 is free from obstructions and functioningproperly.

Likewise, the program logic computer 28 communicates with therecirculation pump 230 to determine whether the pump 230 is functioningproperly. In addition, the program logic computer 28 preferably connectsto a flow meter 258 to sense whether a blockage exists in therecirculation system 24 and whether the recirculation pump 230 isadequately functioning. If the pump 230 is functioning improperly, or ifthe flow through the recirculation system 24 is below the desired level,the program logic computer 28 activates an indicator light 18 on thepanel 16 of the disposal unit 10 and will not activate the disposer unit10 until the problem has been corrected.

In addition to monitoring the disposal unit 10 as discussed above, theprogram logic computer 28 also controls the operations of the disposalunit 10. With the micro-switch 250 activated, the program logic computer28 energizes the motor 108 connected to the hopper gate 34 andthereafter energizes the disposer 22 for a preselected grinding period.Preferably the grinding period is less than 20 minutes, more preferablyranges between 0.1 and 5 minutes, and most preferably equals about 3minutes. During the grinding cycle, the program logic computer 28 alsoactivates the recirculation pump 230 to pump sterilant from the holdingtank 220 into the grinding chamber 32 of the disposer 22. The programlogic computer 28 shuts off the disposal unit 10 at the expiration ofthe disposal period.

Method of Use

The above described waste disposal unit 10 and wall-safe 30 are designedto be used in connection with a waste disposal management system. Thewaste management system comprises method of disposing infectious medicalsharps while minimizing human contact with the medical waste.

The system involves placing at least one, and preferably a plurality ofwall-safes 30 throughout a medical facility. Medical personnel depositused syringes, needles, and the like sharps in the wall-safe 30 fordisposal. A technician periodically collects the wall-safes 30 anddelivers them to a room of the medical facility containing at least onedisposal unit 10, typically the basement of a medical facility. Thetechnician replaces filled wall-safes 30 with fresh wall-safes 30 toprevent the wall-safes 30 from completely filling, thereby maintaining adepository for the used medical sharps.

The technician engages the wall-safe 30 with the disposal unit 10 todispose of the medical waste contained in the wall-safe 30. That is, thetechnician places the pegs 74 of the wall-safe 30 into the holes 98 ofthe hopper mechanism platform 90. Positioned accordingly, in theembodiment illustrated in FIG. 7b, the wall-safe 30 triggers themicro-switch which causes the retractable aperture lid 100 to open.Alternatively, the technician lifts the lid 99 in the embodimentillustrated in FIG. 7a to expose the central aperture 94. The technicianthen unlocks the bottom door 64 and slides the wall-safe 30 towards therear of the disposal unit 10; the wall-safe door 64 remains stationary.In this manner, the technician opens the bottom aperture 60 of thewall-safe 30 contacting only the handle 76 of the wall-safe 30.

The contents, including the blotter or disposable cellophane tray 78,fall into the upper portion 112 of the disposer chute 104 with thebottom tray 64 and the retractable aperture lid 100 open. The wall-safeactivates the rocker switch 250 when positioned over the open centralaperture 94. In the embodiment of FIG. 7b, removal of the wall-safe 30from the platform 90 causes the aperture door 100 to retract in order toshield the technician from the medical waste now deposited in thedisposal unit 10.

The program logic computer 28 begins the disposal cycle operation withthe rocker switch 250 being triggered by the wall-safe 30. The programlogic computer 28 checks the following parameters, as described above:(1) whether the waste receptacle 28 is full; (2) whether the chemicaltank 234 is empty; (3) whether the recirculation pump 230 is functioningproperly; (4) whether the disposal 22 is free from obstructions; and (5)whether the sterilant in the holding tank 230 has a concentration offree, available chlorine above a minimum preselected concentrationlevel. If any one of these parameters is not acceptable, the programlogic computer 28 lights the appropriate indicator light(s) 18 on thecabinet panel 16 and will not operate the disposal unit 10 until allparameters are acceptable.

The program logic computer 28, having complete its pre-check of thedisposal unit components, energizes the hopper gate 34 to drop themedical waste contained in the upper portion 112 of the disposal chute104 into the grinding chamber 32. The hopper gate 34 subsequently returnto a position closing the grinding chamber 32 from the upper portion 112of the disposal chute 104. The hopper gate 34 therefore prevents fluidin the grinding chamber 32 from splashing back through the centralaperture 94 of the platform 90 as the medical waste is emptied from thewall-safe 30.

The program logic computer 28 subsequently energizes the disposer 22 togrind the medical waste and sharps into small bits and pieces. As thedisk 148 rotates, the hammers 160 of the disk 148 shatter large items,the shear ring 124 traps waste material forcing the material against thecutting blocks 156, the cutting blocks 156 cut the waste material withthe edges of the shear ring 124 shearing the material into smallparticles, and the cutting blades 158 slice the waste material intosmall fragments.

Simultaneously, the program logic computer 28 activates therecirculation pump 230 to spray sterilant from the holding tank 220 intothe grinding chamber 32. The sterilant generally sterilizes the groundmedical waste. The slurry of medical waste and sterilant passes throughthe cutting assembly 122, through the discharge chamber 128 and throughthe discharge port 36 into the discharge conduit 138. The medical wastedeposits into the waste receptacle 26 and the excess sterilant isrecovered through the effluent port 42, as described above.

The program logic computer 28 activates the vibrators 208 during thethird disposal cycle to enhance sterilant flow through the wastereceptacle 26. It has been determined that vibrating the wastereceptacle 26 during the first few cycles is not necessary because ofthe small volume of waste contained in the waste receptacle 26, andvibrating small volumes of the waste tends to cause waste to escapethrough the filter apertures 198, 204. During the third cycle, however,the deposited waste partially blocks the filter 44 and the vibration isdesired to enhance sterilant flow through the effluent port 42.

In a preferred embodiment, the waste receptacle 26 fills with processedmedical waste after about eight (8) disposal cycles. The program controlcomputer 28 lights the indicator light 18 telling the technician toreplace the waste receptacle 26 before beginning the next disposalcycle. The disposal unit 10 will not work until the technician changesthe waste receptacle 26.

The technician opens the front door 15 of the disposal unit cabinet 12to change the waste receptacle 26. The technician removes the dischargeconduit 38 from the influent port 40 of the waste receptacle 26 andscrews the top end cap 178 onto the influent port 40. Grabbing thehandle 180 of the receptacle 26, the technician slides the receptacle 26from between brackets 206 to a position holding the effluent port 42 ofthe receptacle 26 over the holding tank 220. The technician screws thelower cap 194 onto the effluent port 42 to seal the waste receptacle 26.The technician subsequently disposes the waste receptacle 26 as ordinaryrefuse, typically by placing it in a refuse dumpster for disposal in alandfill.

Before replacing the waste receptacle 26, the technician preferablyreplaces the sterilant in the holding tank 220. The technician opens thegate valve 226 which places the holding tank 220 in communication with aconventional sewer or chemical reclaim drain. The sterilant in holdingtank 220 drains from the holding tank 220. The technician subsequentlyflushes the holding tank 220 with water using a rinse sprayer 260. Thetechnician closes the gate valve 226 after rinsing the holding tank 220.Thereafter, the technician replaces the waste receptacle 26, pushes thereset button 254 and closes the cabinet door 15. The program logiccomputer 28 then fills the holding tank 220 with sterilant having thedesired concentration of free, available chlorine, as described above.

Advantageously, the technician does not contact the pre-processed orprocessed medical waste at any point of the waste management cycle.After the medical waste is deposited in the wall-safe, human hands donot touch the contaminated waste. During the destruction anddecontamination process, the technician is completely shielded from themedical waste, even when initially placing the waste into the disposalunit. Moreover, the technician only contacts the waste receptacle afterprocessing the medical waste, thus safeguarding the technician againstinfection from the medical waste, when operated properly.

Although this invention has been described in terms of a certainpreferred embodiment, other embodiments apparent to those of ordinaryskill in the art are also within the scope of the invention.Accordingly, the scope of the invention is intended to be defined onlyby the claims which follow.

What is claimed is:
 1. A disposal apparatus for processing hospitalwaste, including medical waste and medical sharps, said disposalapparatus comprising a disposer for processing the waste into smallparticles of processed waste, a sterilant recirculation system fordelivering sterilant into said disposer, and a waste receptacle for saidprocessed waste, said waste receptacle comprising an influent portthrough which said processed waste enters said receptacle, a containerthat holds said processed waste from said disposer, said container beingconstructed of a fluid impermeable material, an effluent port throughwhich said sterilant exits said container, and a filter positionedbetween said container and said effluent port, said sterilantrecirculation system extending between said disposer and said wastereceptacle to circulate sterilant between said disposer and said wastereceptacle and to capture sterilant flowing through said effluent portof said waste receptacle.
 2. The disposal apparatus of claim 1, whereinsaid waste receptacle comprises a first cap and a second cap, said firstcap being configured to fasten to said influent port and said second capbeing configured to fasten to said effluent port to seal said wastereceptacle.
 3. The disposal apparatus of claim 1, wherein said effluentport is positioned at the bottom of said waste receptacle.
 4. Thedisposal apparatus of claim 1, wherein said waste receptacle generallyhas a funnel-like shape to maximize drainage through said wastereceptacle.
 5. The disposal apparatus of claim 1, additionallycomprising a reservoir for holding a volume of said sterilant.
 6. Thedisposal apparatus of claim 5, wherein said reservoir is positionedbelow said waste receptacle to capture excess sterilant passing throughsaid effluent port.
 7. The apparatus of claim 1 wherein said sterilantis a liquid disinfectant.
 8. The disposal apparatus of claim 7, whereinsaid reservoir is in selective communication with a chemical supplysource and with a water supply source.
 9. The disposal apparatus ofclaim 8, further comprising a microprocessor and at least one detectorfor monitoring the sterilant and automatically introducing chemical fromthe chemical supply source into the sterilant based upon a preselectedconcentration criteria.
 10. The disposal apparatus of claim 9, whereinsaid sterilant comprises water and chlorine.
 11. The disposal apparatusof claim 9, wherein the preselected concentration criteria comprises anaqueous solution having within the range of from about 2000 ppm to about8000 ppm chemical agent.
 12. A disposal apparatus for processinghospital waste, including medical waste and medical sharps, saiddisposal apparatus comprising:a disposer for processing the waste intosmall particles of processed waste, said disposer comprising:a grindingchamber which receives the waste; a shear ring defining an interiorannular surface supporting an array of spaced teeth which projectinwardly towards the center of said shear ring, each tooth extendingfrom said interior annular surface at an angle from and in a planeparallel to a central vertical axis of said disposer, each tooth havinga generally flat, bottom surface defining a shearing edge, a pluralityof said teeth comprising top portions extending above the tops of theother said teeth and at a greater angle relative to said central axis todefine inverted, generally L-shaped teeth in said array of spaced teeth;and a disk rotatable about said central axis, said disk carrying acutter element forming a shearing surface and positioned to engage saidshearing surfaces defined by the array of teeth and to cooperate withsaid teeth to shear the waste as said disk rotates; a disposable wastereceptacle which receives said processed waste from said disposer, saidwaste receptacle comprising:an influent port through which saidprocessed waste enters said receptacle; a container that holds saidprocessed waste from said disposer, said container being constructed ofa fluid impermeable material; an effluent port through which saidsterilant exits said container; and a filter positioned between saidcontainer and said effluent port; and a sterilant recirculation systemthat circulates sterilant between said disposer and said wastereceptacle and captures sterilant flowing through said effluent port ofsaid waste receptacle.
 13. The disposal apparatus of claim 12additionally comprising a flat blade extending from said disk tojuxtapose said teeth bottoms for cooperating with said shearing edge.14. The disposal apparatus of claim 12, wherein said shear ringadditionally comprises a plurality of elongated teeth extending abovethe tops of the adjacent teeth.
 15. The disposal apparatus of claim 12,wherein said teeth of said shear ring are angled from a central axis ofsaid disposer by about 45°.
 16. The disposal apparatus of claim 12,wherein said disk comprises at least one hammer extending upwardly froma top surface of said disk.
 17. The disposal apparatus of claim 12,additionally comprising a drive motor connected to said disk.
 18. Thedisposal apparatus of claim 1 additionally comprising a microprocessorcontrolling the operation of the apparatus.
 19. The apparatus of claim1, wherein said waste receptacle is puncture resistant.
 20. Theapparatus of claim 1, wherein said influent port and said effluent porteach have a longitudinal axis that is defined by the direction of flowof said sterilant through said port, said longitudinal axes being offsetfrom each another.
 21. The apparatus of claim 12, additionallycomprising a reservoir for holding a volume of said sterilant.
 22. Theapparatus of claim 21, wherein said sterilant recirculation systemcirculates said sterilant from said reservoir to said disposer throughsaid influent port to said container through said filter and saideffluent port and back to said reservoir.